VDSL Performance & Tuning

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Lizard Networks

#829517 2-Jun-2013 09:47

sidefx: Interesting mine generally seem to line up pretty well, but maybe that's cause they're more consistent.

yep, when your rates are consistent (well as much as random errors can be anyway) then it lines up fine.. it seems to take averages for each of them i assume based on different values (hourly, daily 12 hourly, weekly all different average the device itself takes)

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stevehodge

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#829617 2-Jun-2013 13:31

@insane: I think the 'overall' attenuation is calculated based on an average of the 2 attenuation figures. This would give you an attenuation of 6.2, which might be too high for 17a.

6.2db seems too high given the sync rate. The total attenuation figure shows 4db which seems more reasonable. I don't think you can just average the attenuation of the bands to get an overall figure because the bandwidth is not evenly distributed between the bands. If band 1 has more capacity than band 2 then the overall figure should be lower than the average.

stevehodge

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#829618 2-Jun-2013 13:32

As for my woes, I took a quick walk up and down our street and noticed that just 2 houses down from us one of the street lamps is flickering away\barely working... I wonder if that could cause it. I'll report it to the council and see if it improves when they replace it.

I bet that light is the cause.

sidefx

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#829619 2-Jun-2013 13:43

I seriously hope so. Looking at the errors last night I wouldn't be surprised if it drops me down to DLM3 before they replace it though :(

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SamF

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#829650 2-Jun-2013 14:35

stevehodge:
@insane: I think the 'overall' attenuation is calculated based on an average of the 2 attenuation figures. This would give you an attenuation of 6.2, which might be too high for 17a.

6.2db seems too high given the sync rate. The total attenuation figure shows 4db which seems more reasonable. I don't think you can just average the attenuation of the bands to get an overall figure because the bandwidth is not evenly distributed between the bands. If band 1 has more capacity than band 2 then the overall figure should be lower than the average.

Ah yeah, I missed that, 4db seems more like it.

stevehodge

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#829664 2-Jun-2013 15:27

sidefx: I seriously hope so. Looking at the errors last night I wouldn't be surprised if it drops me down to DLM3 before they replace it though :(

Have you tried moving the modem around? It's probably the line picking up the interference but who knows?

Don't forget to ask for a DLM reset when the light is fixed.

cws82us

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#829705 2-Jun-2013 17:12

SamF: @cws82us: Hi & welcome to the thread! I take it you've just been hooked up to VDSL?

Yea. its connected to the phone line. I only got one Phone juck so I guess that be fine.

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SamF

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#829749 2-Jun-2013 19:40

Found this in my travels today. It's some interesting real-world examples of what is possible on unrestricted VDSL lines.

http://www.thinkbroadband.com/news/5160-origin-shows-what-speeds-vdsl2-can-achieve.html

insane

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#829813 2-Jun-2013 21:57

SamF:
stevehodge:
@insane: I think the 'overall' attenuation is calculated based on an average of the 2 attenuation figures. This would give you an attenuation of 6.2, which might be too high for 17a.

6.2db seems too high given the sync rate. The total attenuation figure shows 4db which seems more reasonable. I don't think you can just average the attenuation of the bands to get an overall figure because the bandwidth is not evenly distributed between the bands. If band 1 has more capacity than band 2 then the overall figure should be lower than the average.

Ah yeah, I missed that, 4db seems more like it.

Stupid errors, kicked me back to something other than DLM1, maybe DLM2? but enough to get my latency back to 8ms *sigh*

SamF

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#829832 2-Jun-2013 22:28

My errors have been steadily rising over the last week, 2.5 up to 5.5!

seatil

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#829911 3-Jun-2013 07:46

I got VDSL enabled last Tuesday. Lifestyle block gate is 200m from the cabinet by road, probably closer to 250m of overhead cabling if I'm looking at the right poles, and then another 300m or so underneath paddocks to where it enters under the house. At that point the first pair is scotch lock connected to a 2.5m length of solid core cat5e that pops through the floor and is terminated with a (solid core again) RJ45 connector that goes straight into the back of the VDSL modem. Naked VDSL, no splitter, no other internal wiring coming off the incoming cable.

I haven't seen any evidence of DLM activity in the 6 days since we connected. We synced straight up at "Fast" latency (whatever "Fast" means), bitswap on and 0.0 INP downstream and 0.1 INP upstream.

From what I can tell, having read a good 80% of this thread, is that despite the extremely low error rate, our attenuation is likely too high to be moved onto 17a. Our only easy option to increase downstream sync rate will likely be SNR tweaking. (The hard option involves getting the ETP moved to the gate, terminating the DSL line there, and point to point wireless to get back to the house.)

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SamF

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#829971 3-Jun-2013 11:24

@seatil: Congrats, you have done everything right and as a consequence you have been put straight onto DLM-1 (that's what 'fast' means for your firmware). Also, your line looks pretty damn sweet for the distance you are from the cabinet! You are correct about 17a and IMO you currently have the best connection you are likely to be able to get in your circumstances.

The really good news is that your VERY clean error rate (practically 0) bodes very well for SNRM tweaking. I'd take a big jump straight to -5db if I were you and see how you go. Remember you can go to a CRCPM of 10 before you drop from DLM-1. I reckon you'd likely see at least 50mbit fairly comfortably and possibly higher. I'd aim for a CRCPM of <5 to be safe for now; we're seeing a lot of increases in CRCs across the board at the moment - most likely to be due to the weather / change in season.

IMO your idea of moving the ETP to the gate and then running wireless from there is only going to swap DSL issues for wireless issues so I'd stick with what you have now if I were you.

Oh, and congrats also on reading 80% of this thread! That's a lot of reading man!! :D

seatil

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#829979 3-Jun-2013 11:51

We haven't had any rain of consequence in the week we've been connected, so I think I'll hold off on the SNR tweaking until I've seen what a decent rainstorm does. ;-) Better to tweak SNR under the worst-case conditions and get something that will always be stable than to mess around under optimum conditions and risk being rapidly shifted backwards on DLM the moment it rains.

eXDee

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#830006 3-Jun-2013 12:59

Something changed at 4:10am... obviously DLM changes something that the modem does not show:

hio77

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#830014 3-Jun-2013 13:17

cant say i can see a single change in there.. some sort of change in the DSLAM itself i suppose? ild suggest a change in power levels, but thats controlled by the VDSL profile..

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Any comments made are personal opinion and do not reflect directly on the position my current or past employers may have.

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